Sakai is an open source, web-based, Collaboration and Learning Environment (CLE) that is primarily focused on higher education, and has been adopted by hundreds of institutions. It supports the activities of students, teachers, and researchers. Sakai also provides an administrative interface. Sakai is flexible, and can be configured for a variety of specialized audiences.

While Sakai can be used to support research and general-purpose collaborations, it is most widely deployed as a Learning Management System (LMS) or a Virtual Learning Environment (VLE). Sakai provides users with learning, portfolio, library, and project tools. Teachers can create course sites and add chatrooms, forums, blogs, wikis, and a range of other tools. Students can use the tools to undertake activities related to learning, including uploading assignments, completing tests, and interacting with instructors and classmates. Finally, researchers and groups of peers can create project sites for sharing materials and specific interactions. Sakai is designed to be flexible, and has a set of frameworks (internal structures) that make it easier for those who want to build their own tools or services with it.

Sakai is capable of scaling to even the largest and most demanding environments. Indiana University, for example, maintains a deployment for at least 100,000 students. The University of Michigan deploys for 70,000 students. UNISA, in South Africa, deploys to over 200,000 learners and academic staff.